net: Discard and warn about LRO'd skbs received for forwarding

Add skb_warn_if_lro() to test whether an skb was received with LRO and
warn if so.

Change br_forward(), ip_forward() and ip6_forward() to call it) and
discard the skb if it returns true.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 299ec4b..2220b9e 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1702,6 +1702,20 @@ static inline int skb_is_gso_v6(const struct sk_buff *skb)
        return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
 }
 
+extern void __skb_warn_lro_forwarding(const struct sk_buff *skb);
+
+static inline bool skb_warn_if_lro(const struct sk_buff *skb)
+{
+       /* LRO sets gso_size but not gso_type, whereas if GSO is really
+        * wanted then gso_type will be set. */
+       struct skb_shared_info *shinfo = skb_shinfo(skb);
+       if (shinfo->gso_size != 0 && unlikely(shinfo->gso_type == 0)) {
+               __skb_warn_lro_forwarding(skb);
+               return true;
+       }
+       return false;
+}
+
 static inline void skb_forward_csum(struct sk_buff *skb)
 {
        /* Unfortunately we don't support this one.  Any brave souls? */

diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
index 5126457..bdd9cce 100644 (file)
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -89,7 +89,7 @@ void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 /* called with rcu_read_lock */
 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
 {
-       if (should_deliver(to, skb)) {
+       if (!skb_warn_if_lro(skb) && should_deliver(to, skb)) {
                __br_forward(to, skb);
                return;
        }

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 3e18f85..2df012b 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2583,6 +2583,13 @@ bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
        return true;
 }
 
+void __skb_warn_lro_forwarding(const struct sk_buff *skb)
+{
+       if (net_ratelimit())
+               pr_warning("%s: received packets cannot be forwarded"
+                          " while LRO is enabled\n", skb->dev->name);
+}
+
 EXPORT_SYMBOL(___pskb_trim);
 EXPORT_SYMBOL(__kfree_skb);
 EXPORT_SYMBOL(kfree_skb);
@@ -2616,6 +2623,7 @@ EXPORT_SYMBOL(skb_seq_read);
 EXPORT_SYMBOL(skb_abort_seq_read);
 EXPORT_SYMBOL(skb_find_text);
 EXPORT_SYMBOL(skb_append_datato_frags);
+EXPORT_SYMBOL(__skb_warn_lro_forwarding);
 
 EXPORT_SYMBOL_GPL(skb_to_sgvec);
 EXPORT_SYMBOL_GPL(skb_cow_data);

diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
index 37d36a3..da14725 100644 (file)
--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -56,6 +56,9 @@ int ip_forward(struct sk_buff *skb)
        struct rtable *rt;      /* Route we use */
        struct ip_options * opt = &(IPCB(skb)->opt);
 
+       if (skb_warn_if_lro(skb))
+               goto drop;
+
        if (!xfrm4_policy_check(NULL, XFRM_POLICY_FWD, skb))
                goto drop;
 

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 40a2813..fd7cd1b 100644 (file)
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -407,6 +407,9 @@ int ip6_forward(struct sk_buff *skb)
        if (ipv6_devconf.forwarding == 0)
                goto error;
 
+       if (skb_warn_if_lro(skb))
+               goto drop;
+
        if (!xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) {
                IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS);
                goto drop;